EGSA Voltage Regulation and Excitation Questions and Answers

Question 1

When two generators are operating in parallel, what is the primary role of the Automatic Voltage Regulator's (AVR) droop setting?

Accepted Answer

To ensure proportional sharing of reactive power (kVAR) between the generators.

Answer

To control the sharing of real power (kW) between the generators.

Answer

To maintain a constant system frequency regardless of the total load.

Answer

To increase the total voltage output of the paralleled system.

Question 2

A generator set is equipped with a Permanent Magnet Generator (PMG) excitation system. What is the primary advantage of this system compared to a standard self-excited (shunt) system?

Accepted Answer

It isolates the AVR's power source from the main generator output, improving performance under non-linear loads.

Answer

It eliminates the need for an Automatic Voltage Regulator (AVR).

Answer

It provides a lower initial manufacturing cost.

Answer

It generates DC voltage directly without the need for a rectifier.

Question 3

A technician is performing 'field flashing' on a self-excited generator that has lost its residual magnetism. What is the correct procedure?

Accepted Answer

Momentarily applying a DC voltage source, like a battery, to the exciter field windings while the generator is stopped.

Answer

Applying AC voltage from the mains to the generator's output terminals while it is running.

Answer

Connecting a drill to the output and spinning it in reverse to induce a current.

Answer

Short-circuiting the stator windings to create a large current surge.

Question 4

Which of the following conditions is a primary cause of generator overexcitation?

Accepted Answer

A sudden, complete loss of load (load rejection) while the AVR is in manual or fails to respond quickly.

Answer

A sudden, large increase in resistive load.

Answer

Operating the generator at a frequency significantly higher than its rating.

Answer

A short circuit in the stator windings.

Question 5

A data center requires extremely precise voltage regulation (±0.5%) and fast response to load changes. Which type of Automatic Voltage Regulator (AVR) technology is best suited for this critical application?

Accepted Answer

Digital AVR.

Answer

Analog AVR with droop compensation.

Answer

Transformer-based voltage regulator.

Answer

Electromechanical (carbon pile) regulator.

Question 6

While commissioning two paralleled generators, a technician observes a large circulating current between them, and one unit shows a leading power factor while the other shows a lagging power factor, even with no external load. This indicates an issue with:

Accepted Answer

the AVR voltage setpoints or droop settings being mismatched.

Answer

the governor speed settings.

Answer

the phase sequence of one generator being reversed.

Answer

the fuel supply to one of the engines.